Superheater



Feb. 2, 1932.

A. HUET v 1,843,132

SUPERHEATER Filed May 11, 1929 2 Sheets-Sheet 1 fina flue INVENTOR.

- A TTORNEY.

Feb. 2, 1932. A HUET 1,843,132

' SUPERHEATER Filed May 11, 1929 2 Sheets-Sheet 2 1 N VEN TOR.

A TTORNE Y.

Patented Feb. 2, 1932 warren sra'rss PATENT OFFE ANDRE HUET', or PARIS, FRANCE, Assrenoa TO THE SUPER-HEATER COMPANY, or NEW YORK, n. Y.

SUPERHEATER Application filed May 11, 1929, Serial No. 362,322, and. in France May 12, 1928.

The invention relates to superheaters which comprise tubular serpentine units through which the steam circulates as it is being superheated and has for its object the provision of such superheater elements that will not become distorted in use. On account of this absence of distortion, the new units are especially well adapted for making bafies of adjacent lengths of the elements in the 10 manner hereinafter described.

The invention will be described in connection with the drawings herewith in which Fig. 1 shows a superheater element in accordance with the improvement; Fig. 2 shows 15 such an element shaped to form a bafiie; Fig. 3 is a section on line 3-3 of Fig. 2; Fig. 4 is a further figure illustrating a unit when there are two baffles provided; and Fig. 5 is a section on line 5-5 of Fig. 2 looking in the direction indicated by the arrows.

In Fig.1 the steam is admitted to the header 1 and is taken off from header 2, these two headers being of any desired construction. Attached to them is a plurality of supe-rheater elements of which one is shown at 3. The gases heating the superheater are assumed to flow in the opposite direction from the steam flow as indicated by the arrows 1, although this is not essential. The

rate of' expansion of the length or leg from the point 6 to the point 7 as its temperature rises from ordinary atmospheric temperature to operating temperatures will be different from the rate of expansion of the length or leg 8 and the latter in turn will be different from the rate of expansion of the length or leg 9 which in turn varies from that of length 10 and so on progressively to Y, the lengths 11 and 12. This difference is due to the differing temperatures of the metal. The temperature of the metal at any given point is only a little higher than that of the steam flowing through the element at that point. The steam temperature increases gradually from the point of inlet to the point of outlet, and the expansion per unit length of the straight portions increases correspondingly from the inlet towards the outlet. y, Thus the metal in the leg 5 expands at a somewhat smaller rate per unit length than the metal in the leg 8. To compensate for this different rate of expansion the legs are made of unequal length, the cooler leg being made longer by an amount corresponding to the difference in temperature. As a result the points 15 and 16 will remain relatively fixed although the point 7 will move away from both of them. Similarly the rate of expansion between 8 and 9 will vary but the total expansion of the legs 8 and 9 will be the same so that point 14 will remain fixed relatively to 7. Similarly the point 17 will remain fixed relatively to 16, the point 18 will remain fixed relatively to 14 and 7 and so on to the end so that the point 19 is fixed relatively to 18, .14: and 7 and the point 20 is fixed relatively to the points 17, 16 and 6.

As a result there is no distortion of the'elements such asoccurs frequently in practice when all of the straight portions 5 to 12 are made equal in length. It is obvious that the amount by which the straight portions must progressively be relatively shortened will depend upon the circumstances such as the temperature of the steam at the inlet, its temperature at the outlet and the rate of heat-transfer. These are quantities which can all be determined quite closely so that the relative lengths necessary for these straight portions can be quite closely calculated.

With an element of this general type in which there is no material distortion, it is quite feasible to construct baffles according to the plan next to be described in connection with Figs. 2, 3 and 5. The lengths of the straight portions 5, 8, 9, etc. are again shown as progressively diminishing in accordance with theabove description. At a point near the middle of this superheater is shown a baflie made by bending into a common plane the two'straight portions 21 and 22 of the first element, 24 and 25 of the next element, and so on. Instead of connecting their right-hand ends by means of a loop such as those connecting the ends of the straightportions elsewhere, returnbends as shown at 23 are used. These return bends are of such shape thatthe two legs 21 and 22, 24 and 25, etc.,are closely adjacent to each other. The spacing of the several superheater elements is such that the adjacent legs of neighboring units are substantially in contact with each other. In this manner a bafile is constructed. The absence of any distortion in the several lengths will keep the baifle tight. If an attempt were made to build such abaflle with a set of elements in which the several straight portions were all of the same length it would be impossible to keep the bafiie tigth on 210- 7 count of the warping of the units. c

Referring to Fig. 4 there are here shown two lea-flies 26 and 27 formed similarly to the one described in connection with Figs. 2 and 3. Thestraight portions of the elements fluid is cooled, and the temperature of the fluid and therefore of the tubes progressively diminishes from inlet to outlet. The straight lengths in. any case vary in length to compensate for the difl'erent rates of expansion.

I claim: 1. In apparatus of the class described, the

combination of two fixed headers and a plurality of tubular elements through which a fluid to be heated'flows,' each element comprising a plurality 'of parallel straight portions progressively diminishing'in length in a the direction of the flow and return'portions connecting them into zig-zag form, the straight portions of each element being in a vertical plane except certain of'them' which lie between straight portions of neighboring elements thereby forming a baflie.

2. In apparatus of the class described a tubular element of zig-zag form through which a fluid flows whose temperature changes progressively from inlet to outlet, the lengths of the several straight portions of the element being; progressively dili'erent by amounts substantially to equalize the total expansions of the several straight portions.

3. In apparatus of the class described, a tubular'element through which a fluid to be heatedflows, the element being of zig-zag formation and the several straight portions being of progressively decreasing length in the direction of the .fiuid flow, the decrease being such as substantially to equalize the total expansions'of the several straight portions.

4. In apparatus of the class described, the combination of two fixed headers and a plurality of tubular elements through which a fluid t'o be heated flows, each element being zig-aag inform with an even number of straight portions, the straight portions progresslvely dlmlnishing in'length in the direction of the flow, the elements being in spaced parallel relation with spaces substantially equal to the tube diameter, some of the straight portions of each element'belng bent into a common plane to form a battle.

ANDRE HUET. 

